Soft formation core bit cutterhead



Dec. 6, w49 H. E. coNKLlN 2,490,208

SOFT FORMATION CORE BIT CUTTERHEAD Filed April 12d 194e 2 sheets-sheet 2 HJ?. Coni: Zin

Patented Dec. 6, 1 949 UNITED STATES PATENT OFFICE SOFT FORMATION CORE BIT CUTTERHEAD Henry E. Conklin, Houston, Tex.

Application April 12, 1946, Serial No. 661,772

(Cl. Z55-'72) 2 Claims.

This invention relates to soft formation core bit cutterheads as particularly used in the drilling of oil wells, the invention having for its object to provide a cutterhead which is more efficient in operation than those heretofore proposed.

With this and other objects in view, the invention resides in the novel details of construction and combinations of parts as will be disclosed more fully hereinafter and particularly covered by the claims.

Referring to the accompanying drawings forming a part of this specification and in which like numerals designate like parts in all the views- Fig. l is a vertical sectional View of a cutterhead casting made in accordance with this invention, said view being taken as on the contorted line l-l of Fig. 2 and looking in the direction of the arrows;

Fig. 2 is a transverse sectional View of said casting taken as on the line 2-2 of Fig. 1 and looking in the direction of the arrows;

Fig. 3 is a bottom plan view of the cutterhead, particularly illustrating the grooves therein for the reception of the cutter blades; and

Fig. 4 is a side elevational view of the cutterhead. A

In the boring of oil and other wells it is usual practice to attach a cutterhead to the drill shaft, which cutterhead is provided with an axial recess or chamber to receive and hold a core or sample of the strata through which the drill is driven whereby, upon withdrawal of the drill and removal of the cutterhead therefrom, the sample or core can be extracted in its entirety and examined and/or tested to learn the nature of the strata which has been penetrated. Therefore, the cutterhead is provided with two or more cutting blades for not only forming a cylindrical hole in the earth but which are also adapted to extend inwardly, beneath the extremity of the cutterhead, a sufficient distance to carefully cut the bottom surface of said cylindrical hole and permit a cylindrical sample of the strata, which has been penetrated, to pass into the cavity or chamber of the cutterhead and be retained therein by suitable mechanism, so that when the drill shaft and cutterhead are withdrawn from the earth said sample will be extracted therewith.

This invention has to do with the cutterhead only and hence, in the drawings, there has been illustrated merely a casting which later can be machined and/or otherwise formed to receive the mechanism above mentioned for holding the core or sample in the cutterhead. The reason for this is that specifically the invention has to do with the attachment of the cutting blades to the cutterhead, and not with such internal mechanism.

That is to say, heretofore such blades have been attached to the outer surface of the cutterhead as part of the casting in such manner that they become worn and/or broken, particularly when great friction is encountered in the driving of the well as through a dense stratum such as stone, mineral or metal, to the end that portions of the blades are lost in the well or are broken and themselves cause damage to the relatively soft material of the cutterhead, and the restoration of said damaged blades can be accomplished only by building up with weld material or by welding and machining specially designed and adapted parts thereof. Therefore, according to this invention, it is a particular object to provide a cutterhead of such relatively softer material, but to form on the exterior surface thereof a plurality of reinforcements, one for each cutter blade, the said reinforcements extending outwardly from the surface of said cutterhead and milled or otherwise cut to receive a cutter blade, said blade being welded to the reinforcement in such manner that, should the blade later have to be removed from the cutterhead, the such removal may be accomplished readily by cutting away the line of weld, leaving the reinforcement and the cutter blade groove substantially unimpaired and substantially adaptable for the welding in the groove, slot or channel of a new blade, through which procedure the restored head may be used repeatedly.

Referring to the drawings, the cutterhead casting is formed with the conical lower portion 2 and an upper portion 3 which may be substantially cylindrical for the ultimate formation, on the exterior surface thereof, of the threads indicated at 4 for engagement with the lower end of the drill shaft, said casting being provided with the axial bore 5, which bore later may be machined and/or otherwise formed for reception of the core holding mechanism.

The conical portion of said casting is provided 0n its exterior surface with a plurality of ridgelike protuberances or ribs generally identified by the numeral 6 and which may be of any suitable transverse cross section, said ribs in the drawings being illustrated as having a substantially semi-circular cross-section. Each rib does not lie in the plane of an element of the conical surface of the cutterhead, but rather the center-` line or axis of each rib is inclined to a degree equal to that degree which the cutter blade is to have in the completed article, and in Fig. 4 this inclination or angularity has been indicated as 15 to the axial plane of the cutterhead, al though it is to be understood that this angularity may be varied to suit the conditions of well drilling.

After the cutterhead has been cast, each rib is machined, milled or otherwise formed longitudinally with a groove generally identied by the numeral 'I of a size to snugly receive therein a cutter blade 8 as indicated by the dot-and-dash lines. The groove extends into each rib vto such a depth that its bottom surface 9 will lie substantially in the plane of the conical surface of the cutterhead, and the position of the groove in said rib is such that the side I of the groove will lie substantially in the plane of the centerline or axis of said rib, whereby there is left approximately one-half of the rib to serve as a shoulder, abutment, or reinforcement for the cutter blade when positioned in the groove and thus serve to withstand the thrust of the blade due to its frictional engagement with the strata which it cuts. By this construction there is left a relatively small portion Il of the rib on the side of the blade opposite to said abutment, and the blade may be welded in place at the juncture of the blade with the rib portions.

It is obvious that those skilled in the art may vary the details of construction and arrangements of parts without departing from the spirit of the invention, and therefore it is desired not to be limited to the exact foregoing description except as may be required by the claims.

What is claimed is:

1. A soft formation core bit cutterhead for well drilling, comprising a lower portion having a substantially conical exterior surface, and a plurality of substantially identical ribs extending outn wardly from said surface, each rib having an amount of outward extent which is approximately the same throughout the length of the rib, each rib having a substantially semicircular cross-section with the axis of each vrib inclined about 15 to the axial plane of the cutterhead,

each rib having formed therein a groove comprising opposed faces, said groove for the reception of a cutter blade, said groove extending longitudinally of the rib and having one side face lying substantially in the plane of the axis of the rib to form an abutment for the cutter blade, said groove extending inwardly of the rib to approximately the plane of said conical surface.

2. A soft formation core bit cutterhead for well drilling, comprising a lower portion having a substantially conical exterior surface, and a plurality of substantially identical ribs extending outwardly from said surface, each rib having an amount of outward extent which is approximately the same throughout the length of the rib, ea'ch rib 'having a substantially semicircular cross-section with the axis of each rib inclined about 15 to the axial plane of the cutterhead, each rib having formed therein a groove comprising opposed substantially parallel faces, said groove for the reception of a cutter blade, said groove extending longitudinally of the rib and having one side face lying substantially in the plane of the axis of the rib to form an abutment for the cutter blade, said groove extending inwardly of the rib to approximately the 'plane of said conical surface, the area of one of said groove faces being less than the area of the groove face opposite thereto by virtue of the off-center position of said groove in its rib.

HENRY E. CONICLIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name :Date

134,805 Hipkins, Jr Jan. 14, 1873 1,734,469 Journeay Nov. 5, 1929 1,869,843 Cole Aug. 2, 1932 2,182,035 Purnell Dec. 5, 1939 2,188,631 Kraus Jan. 30, `1'940 2,246,812 Pivoto `June 24, 1941 

